The subject matter disclosed herein relates to art of turbomachines and, more particularly, to a system and method for distributing fuel in a turbomachine.
Turbomachines typically include a plurality of combustor assemblies that supply fuel to respective combustion chambers. The fuel is supplied to an endcover that includes a plurality of fuel circuits each of which terminate at a fuel nozzle. In the case of liquid fuel, the endcover includes a flange that links each of the plurality of fuel circuits with a fuel source. The flange feeds the liquid fuel to each nozzle. In addition to fuel, water may be supplied to each nozzle through another flange, and a supplemental atomization air supply may be provided to each nozzle from a compressor.
Initially, fuel and water are delivered to the flange for distribution to all of the fuel circuits on a particular endcover. During certain periods, such as start up, the fuel is passed to each fuel circuit at a low pressure. As such, supplemental atomization air, in the form of compressed air, must be added to ensure proper atomization of the fuel at each nozzle. If the fuel is not properly atomized, combustion may not occur. The compressed air is typically extracted from an intermediate stage of an associated compressor. More specifically, the compressed air is withdrawn from a working fluid path, passed to a supplemental compressor that further increases pressure, and delivered to the endcover to atomize the fuel. Withdrawing air from the working fluid path, lowers turbine operating efficiency. In addition to lowering turbine efficiency, the requirement for the supplemental compressor and associated piping to deliver the compressed air to the endcover increases both capital costs and maintenance and operating costs.